In textile machines which process yarn, it is often necessary to grasp a free end of the yarn and to convey this free end of yarn to another desired location in the textile machine. This is particularly true in the case of a two-for-one twister textile yarn processing machine utilizing pneumatic threading mechanisms for threading-up the spindle assemblies thereof upon starting-up of the spindle assembly or following breakage of the yarn during processing. Such for two-for-one twister textile yarn processing machines with pneumatic threading mechanisms for threading-up the spindle assembly are disclosed in U.S. Pat. 3,731,478, issued May 8, 1973, and U.S. Pat. No. 3,975,893, issued Aug. 24, 1976, both of which are assigned to the assignee of the present invention.
As may be seen in both of these U.S. patents, there is provided a two-for-one twister or the like textile yarn processing machine having a plurality of spindle assemblies mounted in generally side-by-side relationship along the outside of the machine and each including a driven rotating rotor mechanism, a stationary carrier mechanism for carrying a hollow supply package of yarn, and an elongate yarn passageway extending downwardly through the top of the carrier mechanism along the axis of the spindle assembly and radially outwardly through the rotor mechanism for receiving the yarn from the supply package therethrough and then upwardly along the outside of the carrier mechanism for forming a rotating balloon of yarn during yarn processing and which is subsequently taken-up by a take-up mechanism. There is also described in these U.S. patents selectively-operable pneumatic threading mechanisms for automatically threading yarn withdrawn from the supply package through the yarn passageway of the spindle assembly by creating a suction through the yarn entry portion of the passageway and a positive air stream through the yarn exit portion of the passageway.
In order to accomplish suitable pneumatic threading-up with the pneumatic threading mechanisms disclosed in the above U.S. patents, the free end of yarn must be pulled from the supply package of yarn and positioned at the entry of the yarn passageway through the spindle assembly so that the suction may pull the yarn into the yarn passageway and be conveyed through and out of the yarn passageway by the suction and positive air stream created therein.
Accordingly, in the event of a yarn breakage or the start-up of a yarn processing operation, the above manual positioning of the free end of yarn must be performed by an operator at each spindle assembly which utilizes as substantial amount of operator time. No mechanisms have heretofore been proposed for cooperating with pneumatic threading mechanisms of spindle assemblies of textile yarn processing machines for properly positioning a free end of yarn at a desired location in the textile machine for effecting the pneumatic threading-up of the spindle assembly.